Study On Precious Metal Nanocomposites Applied In Anode Catalyst Of Direct Borohydride Fuel Cell

The direct borohydride fuel cell?DBFC?is an energy conversion device using NaBH₄ as a fuel to provide electricity.It possesses high theoretical open circuit voltage?3.01 V?and high energy density(9300 Wh kg^-1),and it is a kind of clean energy source which is environment friendly and renewable.DBFC has a profound application prospect in space equipment,public transportation,portable equipment and other fields.In recent years,DBFC has been widely concerned,and the performance of DBFC is mainly determined by the anode catalyst,for which the research of anode catalyst becomes a key point.Noble metals such as Pt,Pd and Au are commonly used as anode catalysts of DBFC,but high cost of noble metals impede the commercialization of DBFC.Therefore,it is necessary to carry out modification research on the catalyst to improve the performance of the catalyst,so as to reduce the cost of the catalyst.In this paper,noble metal catalysts are modified by doping,and three kinds of DBFC anode catalysts were designed and prepared.As-prepared catalysts are examined by scanning electron microcopy?SEM?,transmission electron microscopy?TEM?,and X-ray diffraction?XRD?to analyze morphology features and microstructures.The performances of catalysts were tested by cyclic voltammetry?CV?,chronopotentiometry?CP?,chronoamperometry?CA?,linear sweep voltammetry?LSV?and other electrochemical testing methods.The main research contents are as follows:1.Au/Ni?OH?₂/C catalysts are facilely prepared via a two-step method.Au nanoparticles dispersedly grow on both carbon support and carbon-supported Ni?OH?₂nanospheres.The results show that appropriate addition of Ni?OH?₂ improves the electrocatalytic activity of catalyst.Au_?50?/Ni?OH?_2?50?/C catalyst displayed the highest electrocatalytic activity for BH₄^-electrooxidation among the as-prepared catalysts,and its current density of BH₄^-electrooxidation reached 33.4 mA cm^-22 in CV test,while the Au/C was 22.8 mA cm^-2 at the same condition.2.Pt/Ni?OH?₂/C catalysts are facilely prepared via a two-step method.Pt nanoparticles dispersedly grow on both carbon support and carbon-supported Ni?OH?₂nanospheres.The results show that appropriate addition of Ni?OH?₂ improves the electrocatalytic activity of catalyst and inhibited the hydrolysis of BH₄^-.Pt_?50?/Ni?OH?_2?50?/C catalyst displayed the highest electrocatalytic activity for BH₄^-electrooxidation among the as-prepared catalysts and its current density of BH₄^-electrooxidation reached 32.8 mA cm^-22 in CV test,while the Pt/C was 18.3 mA cm^-2 at the same condition.3.Co?OH?₂@Au/C catalysts are facilely prepared via a two-step method.Core-shell nanoparticles formed by Co?OH?2 particles coated with the Au layer are dispersed on carbon support.The results show that the core-shell structure increases the active area of Au and electrocatalytic activity of catalyst is improved.Co?OH?₂@Au/C catalyst displayed the highest electrocatalytic activity for BH₄^-electrooxidation among the as-prepared catalysts,and its current density of BH₄^-electrooxidation reached 50.3mA cm^-22 in CV test.